1. Field of the Invention
The present invention relates to a method of manufacturing a liquid crystal display panel composed of an active matrix substrate including a matrix of pixels and a counter substrate located opposed to the active matrix substrate at a required distance, and an aligning apparatus for use in manufacturing the liquid crystal display panel.
2. Description of the Related Art
As electronic equipment provided with a liquid crystal display apparatus, which is represented by a liquid crystal projector, has become widely available in recent years, the need for higher performance of the liquid crystal display apparatus has grown and improvements have been made to enhance the definition and brightness of the liquid crystal display apparatus. A liquid crystal display panel used in the liquid crystal display apparatus is generally composed of an active matrix substrate provided with a matrix of pixels, a TFT (Thin Film Transistor) for pixel control and the like, and a counter substrate provided with a color filter, a black matrix and the like. These substrates are overlaid (aligned) relative to alignment marks, laminated and integrated into one.
FIG. 4 shows a schematic structure of a conventional liquid crystal display panel in assembly. Referring to FIG. 4, a counter substrate 110A is located opposed and parallel to an active matrix substrate 110B, and an alignment mark a and an alignment mark b are formed on the counter substrate 110A and the active matrix substrate 110B, respectively. In laminating the active matrix substrate 110B and the counter substrate 110A in a conventional manner, the alignment marks a and b are simultaneously observed by a microscope 120, and the active matrix substrate 110B is shifted in a horizontal direction by an unillustrated shift table if the alignment marks a and b are displaced from each other, whereby the active matrix substrate 110B and the counter substrate 110A are aligned. A required distance d is provided between the active matrix substrate 110B and the counter substrate 110A because liquid crystal is required to be sealed therein in the later process. When the distance d is about several microns, since both the alignment marks a and b are within the focal depth of the microscope 120, sufficient visibility and precise alignment can be achieved.
However, in such a conventional method, if the distance between the active matrix substrate and the counter substrate increases to about several hundreds of microns, the two alignment marks are out of the focal depth of the microscope, which makes it difficult to simultaneously observe the two alignment marks with high visibility and also lowers alignment precision.